Most of the whole blood collected from donors today is not itself stored and used for transfusion. Instead, the whole blood is separated into its clinically proven components (typically red blood cells, platelets, and plasma), which are themselves individually stored and used to treat a multiplicity of specific conditions and diseased states. For example, the red blood cell component is used to treat anemia; the concentrated platelet component is used to control thrombocytopenic bleeding; and the platelet-poor plasma component is used as a volume expander or as a source of Clotting Factor VIII for the treatment of hemophilia.
Systems composed of multiple, interconnected plastic bags have met widespread use and acceptance in the collection, processing and storage of these blood components. In the United States, these multiple blood bag systems are subject to regulation by the government. For example, the plastic materials from which the bags and tubing are made must be approved by the government. In addition, the maximum storage periods for the blood components collected in these systems are prescribed by regulation.
In the United States, whole blood components collected in a nonsterile, or "open", system (i.e. one that is open to communication with the atmosphere) must, under governmental regulations, be transfused within twenty-four hours. However, when whole blood components are collected in a sterile, or "closed", system (i.e., one that is closed to communication with the atmosphere), the red blood cells can be stored up to forty-two days (depending upon the type of anticoagulant and storage medium used); the platelet concentrate can be stored up to five days (depending upon the type of storage container); and the platelet-poor plasma may be frozen and stored for even longer periods. Conventional systems of multiple, interconnected plastic bags have met with widespread acceptance, because these systems can reliably provide the desired sterile, "closed" environment for blood collection and processing, thereby assuring the maximum available storage periods.
Before transfusing cellular blood components like red blood cells, it is important assure that the blood type of the recipient matches the blood type of the donor. For this reason, conventional blood collection procedures collect several small aliquots or samples of the donated whole blood for use in crossmatching and typing the donor's blood prior to transfusion.
Typically, as FIG. 1 shows, the samples are obtained after collecting the whole blood, by expressing a small amount of the collected whole blood (now mixed with an anticoagulant) from the primary collection bag 2 back into donor tube 4 that is attached to the bag 2. In this process, the phlebotomy needle 6 is removed, and sealed pockets 8 are formed along the length of the donor tube 4, where the samples of the donor's anticoagulated whole blood are retained. The pockets 8 are formed using a conventional heat sealing device (for example, the Hematron.RTM. dielectric sealer sold by Baxter Healthcare Corporation), which forms hermetic, snap-apart seals (designated "S" in FIG. 1) spaced apart along the length of the donor tube 4.
After the whole blood samples are collected in the donor tube 4, conventionally procedures then centrifugally process the whole blood within the primary bag 2 to separate it into red blood cells and platelet-rich plasma. The platelet-rich plasma is expressed from the primary bag 2 into an integrally attached transfer bag 3a for additional processing into platelet-poor plasma and platelet concentrate. The platelet-poor plasma is conveyed into integrally attached transfer bag 3b for storage. The platelet concentrate remains in transfer bag 3a for storage. The red blood cells are retained in the primary bag 2 for storage.
In conventional systems and procedures like that shown in FIG. 1, the donor tube 4 in which the whole blood samples are retained is integrally attached to the primary bag 2, where the cellular red blood cells are ultimately stored. Conventional blood collection systems and procedures therefore serve to preserve a direct link between the donor's whole blood samples and the separated cellular red blood cell components obtained from the donor.
In collecting whole blood components for transfusion, it is desirable to minimize the presence of impurities or other materials that may cause undesired side effects in the recipient. For example, because of possible febrile reactions, it is generally considered desirable to transfuse red blood cells substantially free of the white blood cell components, particularly for recipients who undergo frequent transfusions.
One way to remove white blood cells is by washing the red blood cells with saline. This technique is time consuming and inefficient, as it can reduce the number of red blood cells available for transfusion. The washing process also exposes the red blood cells to communication with the atmosphere, and thereby constitutes a "non-sterile" entry into the storage system. Once a non-sterile entry is made in a previously closed system, the system is considered "opened", and transfusion must occur within twenty-four hours, regardless of the manner in which the blood was collected and processed in the first place. In the United States, an entry into a blood collection system that presents the probability of non-sterility that exceeds one in a million is generally considered to constitute a "non-sterile" entry.
Another way to remove white blood cells is by filtration. Systems and methods for accomplishing this within the context of conventional multiple blood bag configurations are described in Wisdom U.S. Pat. Nos. 4,596,657 and 4,767,541, as well as in Carmen et al U.S. Pat. Nos. 4,810,378 and 4,855,063. In these arrangements, an inline white blood cell filtration device is used. In these arrangements, the red blood cells are transferred out of the primary bag for filtration. After filtration, the red blood cells, now substantially free of white blood cells, are retained in a separate transfer bag for storage.
In using these new systems and methods, it is still necessary to collect samples of the donor's whole blood in the donor tube for crossmatching and typing purposes. However, by transferring the red blood cells out of the original whole blood collection container (to which the donor tube is attached) into a another container for storage, these new systems and methods break the direct physical link that has heretofore existed between the red blood cell storage container and the donor tube, where the samples of the donor's whole blood are retained for analysis
A need still exists for further improved systems and methods for removing undesired matter from blood components prior to transfusion or storage in a way that lends itself to use in closed multiple blood bag system environments and that assures accurate crossmatching and typing of cellular blood components prior to transfusion.